Cementing plugs and float equipment



Dec. 1, 1964 1 B. scoTT CEMENTING PLUGS AND FLOAT EQUIPMENT v 5 Sheets-Sheet l Filed May 13, 1958 INVENTOR, @ze 5. .S60/*7 Dec. 1, 1964 L. B. SCOTT CEMENTING PLUGS AND FLOAT EQUIPMENT 5 Sheets-Sheet 2 Filed May 13, 1958 INVENTOR, #5 5. sco/'fr Dec. 1, 1964 Filed May 13, 1958 L. B. SCOTT 'CEMENTING PLUGS AND FLOAT EQUIPMENT 5 Sheets-Sheet 3 5 Sheets-Sheet 4 INVENToR, f/E 5, ,scarf BY J #Woe/VE# Dec. 1, 1964 1 B. scoTT CEMENTING PLUGS AND FLOAT EQUIPMENT Filed May 13, 1958 5r sheets-sheet. 5%

L. B. SCOTT CEMENTING PLUGS AND FLOAT EQUIPMENT Dec. 1, 1964 Filed May 15, 1958 Il @4M JNVENTOR, ME 5.. taff @frogs/5# United States Patent O 3,159,219 CEMENTENG FLUGS AND FIGA? EQUIPMENT Lyle B. Scott, South Gate, @alitg assigner to Byron Jackson inc.y Fitted May I3, 1958, Ser. No. 734,958 Sli-aims. (Cl. 16u-E55) The present invention relates to cementing equipment for use in cementing well casing in a well bore, and more particularly to apparatus of the type generally referred to as cementing shoes and collars.

Heretofore, it has been the practice in running well casing into a well bore preparatory to cementing the casing in place, to employ a shoe at the lower extremity of the casing, or a collar at a point spaced upwardly from the lower extremity, providing means for controlling the rate of admission of well uids into the casing as the casing passes downwardly into the well bore. Such casing shoes and collars are also characteristically provided with a back pressure check valve which is adapted to enable the circulation of a flushing fluid down through the casing and up through the annulus outside of the casing, this back pressure valve serving to prevent the back-flow of well cement into the casing after the cement has been placed and the pumps at the surface have been shut down.

In initially running the string of casing into a well containing well fluids, it is desirable that the rate of admission of well fluids into the casing be metered or controlled so that surges of fluid will not be created as the downward movement of the casing string is halted during making up of the string from short lengths, otherwise such well fluids will surge up out of the top of the casing string and flow on to the rig floor, causing adverse and hazardous working conditions. ning of casing into relatively deep wells, it is necessary that the casing be filled with fluid in order to prevent casing collapse due to external hydrostatic pressure, and accordingly numerous devices have been contrived for controlling the admission of uids to the casing. t

In accordance with an object of the present invention, a novel. means for controlling or restricting the ow of uid into the casing is provided, wherein a fluid flow controlling or restricting device is employed in the apparatus and is so constructed that the flow of fluid therethrough in one direction is controlled or restricted through v a flexible diaphragm, which will retard the fiow of fluid therethrough at normal pressures encountered during the running of a casing string but which, when subjected to excessive pressuretsurges such as might be caused by running the casing into the Well at an excessive rate, then the diaphragm will flex and permit a greater flow rate therethrough, thus preventing the imposition upon the well formation of undesirable pressures.

The flow controlling or restricting device is, in accordance with a further object of the invention, adapted to be pumped out of the apparatus upon commencement of circulation of fluid downwardly therethrough, thus to leave substantially la full flow passage through the device.

Heretofore, in conventional casing shoes and collars of the type here involved wherein a back-pressure valve is incorporated in the shoe or collar, the constructions have been somewhat complicated by the need for rendering the back-pressure valve inoperative during the period when the casing is being run into the well while freeing the back-pressure valve responsive to the pumping of fluid downwardly therethrough. In addition, the backpressure valve seat, as well as the valve-which has characteristically been of the ball type-are subjected to the wearing `action of the upward flow of fluid through the assembly as the casing is being run in, and are also sub- Particularly in run- 3,l9,2l9 Patented Dec. l, 1954 jected to the wearing effect of fluid being circulated down through the casing string andto the wearing effect of the well cement as it is pumped down through the back-pressure valve. Therefore, because of the substantial abrasive effects of the fluids passing through the conventional backressure valve, such valves have frequently been known to be inoperative due to wear when the pumps at the surface have been shut down following placement of the cement, and as a consequence pressure had to be maintained from the surface, since otherwise the cement might be displaced from the well due to well pressures and forced back into the casing through the inoperative check valves.

In accordance with a primary object of the present invention, a back-pressure valve and cementing plug combination is employed which may be characterised as a free valve, inasmuch as the casing may be run and the circulation of flushing fluid therethrough proceeded with before placing the free valve plug of the present invention into the flow stream. Accordingly, when needed, a backpressure valve which will be in good condition and therefore certain to operate, will be available. In this connection, a novel so-called bottom cementing plug is provided, this bottom cementing plug being combined with a back-pressure valve and being adapted to be interposed in the fluid column being pumped into the well between the flushing uid and the well cement, thus forming a floating barrier therebetween. When the combined back-pressure valve and plug reaches the casing collar or shoe made in accordance with the present invention, as will be hereinafter more particularly pointed out, it willbe latched thereto. Following this, only the cement which is to oe placed will be pumped through the cornbined bottom plug and back-pressure valve, so that effective valve operation upon shutting down the surface pumps will be virtually assured.

Another object of the invention is to provide a casing collar or shoe constituting a seat for a cementing plug, the seat and plug having cooperatively engageable latch means for latching plug into the seat upon engagement thereof together with sealing means to prevent the passage of iuid between the seat and the plug, whereby the plug may be bottomed on the seat and effectively prevent the back flow of cement slurry or other fluid subsequent to latching of the plug into the seating collar therefor.

Another object is to provide a combined bottom plug and back-pressure valve and a latching seat therefor in a casing shoe or collar, wherein the bottom plug is provided with a lower extension having a sealing surface, and wherein the seat is provided with a flexible diaphragm Aengageable with the sealing surface so that fluid pressure from below the seat will maintain a tight seal between the diaphragm and the sealingsurface.

In accordance with the foregoing, it is a general object to provide free valve cementing apparatus, including a casing shoe or collar having a seat for the reception of a bottom cementing plug and a combined .bottom cementing plug and back-pressure valve adapted to be Alatched into the seat as it moves into engagement therewith following passage of the circulating lluid through the seat, and wherein the well cement above the bottom plug will pass through the back-pressure valve incorporated therein without substantial deleterious effect upon the backpressure valve.

Other objects and advantages of the invention will be hereinafter described or will become apparent to those skilled in the art, and the novel features thereof will be defined in the appended claims.

In the accompanying drawings:

FIG. 1 is a view depicting a well into which is being run a string of casing, the lower extremity of which is is broken away and shown in section, the casing being seated;

,FlG. l Vis a transverse sectional -line @-10 of FdG. 8;'v

provided with a shoe in accordance with thel invention,

having incorporated therein one form of'iow controlling device and a seat for a combined free valve and bottom `assumed during lowering of the casing;

.'FIG.V 2 lis an enlarged'vertical sectional view showing 'the flow controlling device and the plug seatin detail;

plug, the flow controllingV device being in the condition f FIGQS is a viewsimilar to FIG. .2 but showing the metering deviceand ap valve in elevation and Vdisplaced fromthe casing'shoe, asfwould occur upon the corinnence#` ment of the pumping'gof vlluid rclown through Vthe casing.

FIG. 4 is a view'similar to FG. 1 and showing a combined bottom plug and baclopressure valve and a top Vplug with a body of cement therebetween, and showing the ow controlling device displaced from the casing shoe; FIG. 5 is a view similar to FIGS.' l and 4, showing nthe bottom plug latched'into the seat andthe top plug lseated upon the bottom plug, with the Vbach-pressure valve functioning to retain the cement -in the space outside ofthe casing, as would occur when a` cementing operation has been completed;

casing so as to: eliminate surges of iuid out .of the upper end of the casing string and onto the rig hoor.

In accordance with the presentinvention, va novel ow controlling device is shown at Y3, this flow controlling l device being disposed inY a central cylindrical socket l in.

the bull nose`2. n Y

Referring particularly device 3 is shown as being in the form of a generally cylindrical molded rubber body 5, having at its upper end a liexible diaphragm o, lprovided with a central opening '7 therethrough. Preferably the body 5 is ymolded about a cylindricalrmetallic reinforcing core 8 having at'its upper extremity an inwardly extending radial reinorcing FIG; 6kis an enlarged ver"cal sectional view, more l ing lof the bottom plug;

FIG. 7 is a view similar to FIG. 6, but showing the vcombined bottom plug andback-pressure valve latched into the s eat therefor, with'thefball valve unseated to i' jenable circulation through `the plug, `and with the Vbarrier -insertdisplaced from the bottom plug and passing downf .wardly through the bull nose of the casing shoe;

'5 "FIG Y8 is an enlarged vertical sectional' view corresponding to FIG.' 7 but showing'the back-pressure valve "particularly showing the details of the combined bottom Y plug/'and' back-pressure valve and the seat therefor, the

` combined bottom plug and back-pressurevalvebeing dis-A posed just above the seat as would occur prior to bottomflange 9 projecting partiallyV into the diaphragm 6.

The' bull nose 2 is provided with, a shoulder' lil, and

interposed between this shoulder and the upper end of the ilow controlling device 3, is aiiexible disc or ilap` valve 1l, provided withV an outer mounting ring l2V clamped between shoulderl lo and the 'upper extremity of the body 5 of the how controlling device, and aap 13 flexibly interconnected with the ring 13 at one side of an opening 'lo throughthe ring l2; Preferably the flap 13 1s an Vintegral part of the ring )l2 and, as indicated, is formed of rubber or other lie ible material, the Vcenter oi' the lisp i3 being reinforced with a metallic insert 'l5 having a central opening lo therethrough.

Diaphragm o is so constructed that it Oilers resistance Y to the passage of fluid upwardly through the central opening 7 and would normally repose as shown'in broken lines in FIG. 2, but when subjected to pressure surges,

asmight be encountered'uponrlowering of thecasing C at an excessive ratethe diaphragm e will iiex upwardly, Y

as Yshown in ulllines in 2, and the opening .'7 will FIG. 9is a transverse sectional' view as .taken'on the Y line9-9 of FIG. 8;

FIG.' 11 is a fragmentary view in vertical section through'a casing shoe showing a modified bull nose and owfcontrolling device, the diaphragm being in a re-l laxed'normal condition;

FIG. 12 is a view corresponding FIG.Vr 13 is a view 'corresponding to FIG.` 1l, but showfing the diaphragm as substantially Vclosing the openings i through the bull nose, as would occur upon initiation of circulation downwardly through the casing string; and

FIG. 14 isa view corresponding toFlG. ll, but'with y `'would occur 'as a result of Ycirculation downwardly through the casing; Like reference nate corresponding parts.

Y As illustrated inthe drawings, the lower extremity of y a string `of casing C has secured thereto,v as uby* a collarl 1, a bull nose 2. yIt will be understood, however, ,thaty within lthe purview ofthe invention, the 'member 2 may crements determined by the length of each new section of casing to be added thereto. Duringrlowering of the cas- ',ing, Huid in the kwell will passupwardly into the casing,

Vand, preferably means are Vordinarily provided to limit,

control or restrict, the passage ofthe -Well-*luid's into the v terno. 11, but-with f A.the diaphragm shown in the condition assumed during Vruiming in of the casing;y

characters ,in the/several figures of the ydrawings and-in the following detailed-description, riesig- View as taken on the Y Y i the ow controlling device ejected from the casing saoe as Y ing in diameter to the opening En', the plate .2 2 having an` lbecome enlarged soas to permit the flow therethrough of aY greater volume of Huid, thus preventing the imposi- Y tion upon the well wall of'excessive pressure pulses.

' However, when the casing C has beenlowered to the desired position ina well, then a lushing fluid is circulated downwardly therethrough Vso as to Vztiush from the well the fluids such as drilling iiuids initially rcontained therein. Under these circumstances it is desirable that Y the clearance through the casing shoe or collar be as large as possible.v Accordingly, the tiap valve 1l provides Vmeans which will close when the circulation of fluid down n through the casing is commenced, and suiiicient pressure will buildupv above the valve. 1i so that the valve ll'and lthe flow `controlling device' 3'will be forced downwardly from the socket 4, as shown in FlG. 3, thus leaving the .bull nose 2 substantially free of any yobstruction `to the ilow of'uid downwardly therethrough. 1 Y

Casing collar l is provided with an internal ilange 17,

and abutting beneath the flange l? is an annular seat member i8 having a conical seating surface lconverg- Vmg rupon a central opening 2li through the'seatl. Dis.

posed beneath the slea ld, is an annular'pla'te 2 1 having a central openingZ?. therethrough, generally correspond# xially extending flange 23 projecting upwardly intoa recess 24 in the innerl peripheryfof the seat l and providing an annular channel in which is disposed a resilient split snap ring 25, fior a lpurpose which will hereinafterV more fully appear. Y Y t Disposed beneath the plate 2l is a resilient sealing embrane or diaphragm '26, having a central opening 27 therethrough. At its outer periphery the membrane V2.6 is provided with an enlarged mounting dange 28 which isbevelled so as to beengaged within a tapered channel 29 provided between the collar l. and the sent l and plate 2l. In orderto retain the seat lrthe plate 2 and themembraneo in assembled relation and vpressed against` the angejl inthe collar l, the bull nose 2 is provided,

*with a'cylindrical neck 3l? which is threadedly connected tothe lower extremity of the `collar l and provides a 'shoulder 3l. opposed to the flange l? inthe collar 1,YV Y `the vshoulder 31 zbeing engaged beneath membrane Z6;

to FG. l2, the llow controlling .Y

Preferably the membrane 26 merely has a sealing function, which will hereinafter more fully appear, and has no flow restricting effect upon iluid passing through the opening 29 in seat 18, but instead is free to open wide, as shown in FIG. 3, as uid is passing downwardly therethrough.

In accordance with one of the salient features of the invention, a combined bottom cementing plug `and backpressure valve is provided whereby the cementing apparatus may be characterized as a free valve type. Such a combined bottom plug and baclopressure valve is generally designated P. structurally, the plug P includes a central valve cage 33, having an internal upwardly tapered valve seat 3d, having a generally Venturi-like central opening 36 therethrough. The seat 3d circumscribes a central passage through the plug P provided by the cage 33. Threadedly, or otherwise suitably secured in the base of the valve cage 33 is a ball valve retainer 37 having a plurality of webs 3S therein adapted to support a ball check valve 39 within the cage 33, while enabling the free flow of fluids between the webs 3S and into a central passage 39 through a downward extension di) of the retainer 37.

Compressed into the opening 39 so kas to prevent the passage of i'iuid therethrough, is a rubber barrier plug 41 which seats against the webs 38 so as to prevent the transfer of uid frombeneath the plug P into the valve cage so long as the barrier 4l is in place.

Molded about the cage 33 is a rubber body d2, having an upper sealing lip 43 and a suitable plurality of axially spaced sealing ribs 4d adapted for sealing engagement with Ithe wall of the casing C. Thus it will be seen that the plug P may be interposed in a tluid column being pumped down the casing C between the ushing fluid and a body of well cement 44 which is to be placed in the well, and the plug P will constitute a oating separator between these two different fluids. As the plug P, interposed between the circulating fluid and the body of cement 44 as indicated in PIG. 4, moves into engagement with the seat i8, as shown in FEGS. 5, 7 and 8, the downward extension 4u of the retainer 37 will pass through the central opening 2li of the seat l, the extension being provided with a tapered nose 45 which `will cam the ring 2.5 in such a manner as to cause a circumferential enlargement of the latter and movement thereof radially outwardly into the recess 24 until such time as the plug P bottoms upon the tapered surface 19 of the seat ld. The downward extension di) of the retainer 37 has an external channel 46 formed therein, into which the ring 25 will expand so as to lock the plug P in engagement with the seat 1S. rFhus, the plug extension lil and the annular seat member have cooperative latch means for latching the plug to the seat.

The sealing membrane 26, previously referred to, provides means for effecting a seal between the plug extension 40 and the collar l, and in this connection it will be noted that the membrane 26 engagesv the tapered nose 45 of extension 49, thus effecting a seal to preclude the passage of uids upwardly between the seat and the retainer 37.

During movement of the plug P downwardly through the entire string of casing C, the barrier 41 effectively precludes the passage of uid upwardly through the cage 33. However, as downward movement of the plug P is halted and the plug is latched into the seat 1S, continued flow of iluid downwardly through the casing under the V pressure of pumps .at the surface will pump the barrier 4l from the opening 39, as indicated in FlG. 7, and the barrier will pass out of the casing sho-e through the open socket 4 as the cement 44 above the plug P passes down through the cage 33, around ball Valve 39 and between webs 38.

In practice, a top plug T will be employed as a floating separator between the cement and another fluid which will be employed to force the cement down through the casing and into the annulus outside the casing, as customary. Upon engagement of the top plug T with the upper end of the bottom plug P, further flow of fluid through the plug P will be prevented, and the rise in pressure at the surface pumps will indicate to the operator that the entire Vbody of cement has been displaced through the plug l and into the well, as desired. lt preferred, however, the bottom plug P may be employed without the top plug T, and other means may be availed o-f for indicating the desired displacement of cement into the well, as is well known in the art.

Turning now to FlGS. ll thru 14, another form of low controlling or restricting device made in accordance with the invention is disclosed. ln these views the casing collar is designated il', and threadedly mounted in the lower extremity thereof is a bull nose 2 having a downwardly opening socket 4, and an outstanding shoulder lll' at the upper end of the socket. Secured in the socket d', by a suitable number of circumferentially spaced shear pins 5t?, is a strainer disc 5l having a suitable number of passages 52 extending therethrough. rhe upper surface of the strainer disc 51 is generally concave and is provided with .an upstanding annular ange 53, about which is disposed a depending complemental flange 54 of a resilient flow controlling or restricting disc or diaphragm 55, the latter being provided with a central opening Se. The normal or relaxed condition of the diaphragm 55 is shown in FIG. ll but upon running a casing string to which the bull nose 2 is attached into a well, fluid will pass through the strainer openings 52, thus effecting upward flexure of the diaphragm S5, as shown in FlG. l2.

As in the embodiment previously described, the diaphragm S5 will ilex more or less, depending upon the rate at which the casing is being lowered in the well so as to permit the passage of fluid upwardly through the opening 56 without imposing undesirable pressure waves upon the well wall W.

When the casing has been lowered to a desired location in the well and the circulation of a llushing lluid is commenced, then, as indicated in FIG. 13, the diaphragm 55 will be flexed downwardly into contact with the concave upper surface of the strainer disc 5l, thus sealing off the majority of thestrainer openings 52. Preferably, however, fthe strainer 5l is provided with a central opening, as illustrated, which underlies the central opening 56 through the diaphragm 55, so as to enable a limited flow of fluid through the strainer Sl. In any event, however, the closure by the diaphragm of the majority of the openings 52 will cause a Sufficient restriction to liow so that the development of pressure above the flow controlling or restricting device will shear ofr' the shear pins E@ and cause the flow controlling or restricting device .to be expelled from the socket 4.

It will be understood that the bull nose 2. and the tiow controlling or restricting mechanism shown therein, may be used as desired in lieu of the bull nose 2 and the flow controlling or restricting device 3.

In the use of the free valve cementing shoe or collar of the invention, as particularly exemplied in FIGS. l, 4 and 5, the string of casing C will be run into the well and the How of well fluids into the casing will be controlled or restricted through the tlow controlling or restricting device 3, or Ithrough that shown in FIGS. ll-l/l, in a controlled manner such as will prevent surges of well fluids upwardly through the casing and onto the well floor when downward movement of the casing string is halted to enable the addition of a furtherlength of casing. When the casing has reached the desired position in the well, as indicated in PEG. 4, fluid will be circulated downwardly through the casing and the llow controlling or restrictmgudevice will be forced out of its socket into the open we After circulation has proceeded for .the desired period of time and the pre-existing lluids in the well, such as drilling mud and the like, have been ushed therefrom, the bottom plug P will be disposed in the casing; and

l above the plug a quantity ovcement 44 will be pumped down through the casing, separated from the iiushing fluid by plug P. The displaceable barrier inscrit 41 in the Vball check valve retainer 37 will maintain separation be tween the ushing lluid and the cement as the rluidspass gdownwardly through the casing, ,until such time as the lplug P bottoms or lands Vupon fthev seat i8 and is latched thereto by engagement of the snap ring 25 in the groove 46 in the. downward extension all yoi the retainer 37.

Further downwmd movement of thecement through the plug P will' displace the barrier "il so thatr it too will pass Vto the bottom of the Well. Pumping oi'ithe cement through the plug l will continue until -thetop plug T Y lands upon the upper end of plug P and indicates, by increased pressure at :the surface, that the Ventire body of cement has been displaced through the plug P into the well, at which time ther pumps may be shut down and back-pressure on the cement will cause the ball check valve@ to close againstballsealt 34, as shown in FlG. 5, thus retaining the cement in place so asto enable it to setup. f Y, y. 1

. it" desired, it ,should be understood that other types of vliuid iiowcontrolling devices may beV employed in lieu of those described `in the foregoing, soV that the casing may gbe iloated intofthe well in a manner Well known in the part. Therefore, the combined bottom plug and backcomprises an annular member removably disposed in said collar, said collar having'an internal shoulder engaged by said. seat, and a kmember threaded into said collar forV Y maintaining said annular seat member in engagement withy Isaid shoulder. y f

7. Apparatus as dened in claim 1, including a flexible membrane projecting into the seat opening, and said'plug pressure valve herein disclosed, is not limited to use in Y a casing shoe or collar wherein-dow Vcontrolling or re- Y stricting devices are employed.

Other changes and alterations may be resorted to withoutfdeparting from the spirit o'V the invention as defined `in .the appended claims.

lclaim: i s 1. Apparatus for use in cementing well casingrin a Well, comprising: a collar adapted to be secured in a casing string, a plug seat in said collar disposed in the path of lluid passing through said `collar, said seat havingan opening for the vpassage of said fluid, a plug havingporf 'tions sealingly engageable with the casing and khaving -meaus to eicct movementof the plug in the casing along f with said duid into engagement with said seat, said seat and said plug having cooperable meansr for latching saidl plug in said seat upon engagement thereof, andA said plug passage of fluid through said plug in the other direction. 2. Apparatus as defined in claim '1, whereinv the means to elect movement of said plug in `said casing includes means displaceably carried bysaid plug for preventing the flow of fluid through said back pressure valve means r in said one directiony While said plug is moving with said fluid in saidcasing. Y v v 3.V Apparatusas delined in'claim 1, wherein said back t pressure valve `means comprises a valve cage in said plug, said cage lhaving'a uid passage therethrough, and a check having Vback pressure valve means for permilttingiluid to i f pass through said plug in one direction but preventing the valve vshiftably disposed in said cage, said cage having a L valve seatengageable by ysaid valve.'

4.' Apparatus as defined in'claim l, wherein said back pressure valve means comprises a valve cage in said plug,

' 'Y said cage having a liuid passage therethrough, and a' check valve shiftahlyl disposedin said cage, said cage having a valveV lseat eugageable by said Vvalve upon movement of the valvelin one direction 'to closesaid fluid passage, a

f depending extension on said cage having a uid passage communicating with said cage, and said means Ito effect movement of said plug in said casing includes a barrier member displace-ably disposed in said passage in .said

extension. 1

5. Apparatus as defined in claim l, wherein said lplug has a depending extensionV provided with-'a fluid .passage f communicating withsaid back pressure valve means, and 1 said means to eleot movement of said plug in saidcasing includes displaceable barrier means blocking said passage in said extension. f

Y 6.1Apparatus as delined in claim 1, wherein said seat having afnose engageable by said membrane when'the plug is latched on said seatffor :sealing the plug and seat,H

against the leakage of iiuid therebetween.

8.' Apparatus as deiinerd in claim 1, including means for'y sealing said plugV and said seat against the leakage of n Y iluid therebetween.

9. Apparatus for use in cementing wellV casing in a Well, compri-sing: a cylindricaly collar to be secured in a casing, an annular member having a seat disposed in said collar and extending radially inwardly, said member having a central opening therethrough, a cementing plug having means to etlect movement of said plug insaid casing along with fluid passing through the casing, said plug having an axial passage therethrough and having a valve Y seat adjacent `the upper end of the passage, a check valve in said passage engageable with said valve seat for pre-kV ventingthe upward flow of iluid through said passage, amemb'er extending downwardly from said-plug for insertion-into the openingfin said annular seat member, and cooperative laltching means on said downwardly extending member and said annular seat member for latching said plug on said seat. v

10.'Apparatus as defined in claim 9, wherein said v latching means includes a resilient snap vring Vcarried' byV one of said members, the other of said membershaving a'groove for reception of said snap ring upon insertion seat member. Y

l1. Apparatus for use in running in and cementing of said,downwardly extending member into said annular Y vwell casingl in a well, comprising: 'a member to be se- Y cured in the casing, said member having a socket the-rein providing a fluid passageway through said member, a flow controlling device having means for restricting the'ow of fluid upwardl t rough said passageway, said liow controlling device being'displaceably disposed in saidsocket,

y'said flow` controlling device also including valve meansY closeable upon the iiow of uid downwardly through the casing for causing the liow controlling device yto be displaced from said socket, and back-pressurevalve means, carried by rsaid member including a back-pressure valve seatY above said ow controlling device for preventing the.

ov/ of fluid upwardly through said casing following dis; placement of said ilow 'controlling device.

12. Apparatus as 4defined in claim 11, wherein said liow restricting means comprises a flexible diaphragm Y Y having a central openingthe'rethrough. Y 1

, 13. Apparatus as defined in claim 11, wherein said liow restrictingV means comprises a flexible diaphragm having a, central opening therethrough, and Vsaid valve means comprises a ilap valve disposed above said diaphragm. f 1 y lll. Apparatus as definedin claim 11, wherein said flow restricting means comprises aexible diaphragm havy ingv a central opening therethrough, and said valve means including a strainer disposed beneath'said diaphragm and `engageable thereby. .v

15; Apparatus as defined in claim 14, including sheard i s able members detachably securing said strainer in said socket. v

ciently `blocking olic the flow of duid downwardly through passageway below said diaphragm, and shearable means connecting said strainer to said member.

20. Apparatus for use in cementing well casing in a well, comprising: an annular member providing a seat and having a central opening, said member being adapted to be disposed in a string of well casing, a resilient diaphragm beneath said annular member and having a central opening smaller than the opening through said annular member, a plug having portions sealingly engageable with the casing and movable in said casing into engagement with said seat along with uid passing through said opening in said annular member, said annular member and said plug having cooperable means for latching said plug on said seat upon engagement of the plug with said seat, and an extension on said plug projectable through the opening in said annular member for sealing engagement by said diaphragm.

2l. Apparatus for use in cementing well casing in a well, comprising: a collar adapted to be secured in a casing string, a plug seat in said collar disposed in the path of uid passing through said collar and having an opening for the passage of said iiuid, a plug having portions sealingly engageable with the casing and movable in the casing along with said Huid into engagement with said seat, said plug having an end extension extendible into the opening in said seat, said seat and said plug extension having cooperable means for latching said plug in said seat upon engagement thereof, and means sealingly engageable with said plug extension to prevent the flow of fluid through the opening in said seat when said plug extension is vdisposed in said opening.

22. Apparatus as defined in claim 21, wherein said latter sealing means includes a diaphragm having a central opening through which said plug extension projects, and a sealing lip extending about said opening in said diaphragm and engageable with said plug extension.

23. Apparatus for use in cementing pipe in a well, comprising the combination of: a plug seat having means for connecting said seat in said pipe in the path of tluid passing through said pipe, said plug seat havng an opening for passage of said fluid, a plug having thereon means sealingly engageable with said pipe to move the plug along with said fluid into engagement with said plug seat, said plug having an extension beneath said sealing means, said extension being extendible into the opening in said seat, said seat and said extension having cooperable means for latching said plug in said seat upon engagement thereof, and said extension and said seat having means including cooperable sealing portions to prevent the flow of fluid upwardly therebetween.

24. Apparatus as defined in claim 23, wherein said last mentioned means comprises a flexible sealing element on one of said portions movable into sealing engagement with the other of said portions.

25. Apparatus as defined in claim 23, wherein the means 26. Apparatus for use in cementing well casing in a I well, comprising: an annular member providing a seat and having a central opening, said member being adapted to be disposed in a string of Well casing, a resilient diaphragm beneath said annular member and having a central opening smaller than the opening through said annular member, a plug having portions sealingly engageable with the casing and movable in said casing into engagement with said seat along with fluid passing through said opening in said annular member, said annular member and said plug having oooperable means for latching said plug on said seat upon engagement of theplug with said seat, an extension on said plug projectable through the opening in said annular member for sealing engagement by said diaphragm, said diaphragm being provided with an outer peripheral sealing portion extending axially thereof, and said annular member having a surface engageable with said peripheral sealing portion to force the latter outwardly.

References Cited in the file of this patent `UNITED STATES PATENTS 2,019,885 Black Nov. 5, 1935 2,169,569 ODonnell Aug. 15, 1939 2,352,744 Stoddard July 4, 1944 2,479,960 Osborn Aug. 23, 1949 2,621,742 Brown Dec. 16, 1952 2,630,178 Brown Mar. 3, 1953 2,642,140 Brown June 16, 1953 2,656,151 Miller Oct. 20, 1953 2,737,247 Baker Mar. 6, 1956 2,799,349 Clark July 16, 1957 

11. APPARATUS FOR USE IN RUNNING IN AND CEMENTING WELL CASING IN A WELL, COMPRISING: A MEMBER TO BE SECURED IN THE CASING, SAID MEMBER HAVING A SOCKET THEREIN PROVIDING A FLUID PASSAGEWAY THROUGH SAID MEMBER, A FLOW CONTROLLING DEVICE HAVING MEANS FOR RESTRICTING THE FLOW OF FLUID UPWARDLY THROUGH SAID PASSAGEWAY, SAID FLOW CONTROLLING DEVICE BEING DISPLACEABLY DISPOSED IN SAID SOCKET, SAID FLOW CONTROLLING DEVICE ALSO INCLUDING VALVE MEANS CLOSEABLE UPON THE FLOW OF FLUID DOWNWARDLY THROUGH THE CASING FOR CAUSING THE FLOW CONTROLLING DEVICE TO BE DISPLACED FROM SAID SOCKET, AND BACK-PRESSURE VALVE MEANS CARRIED BY SAID MEMBER INCLUDING A BACK-PRESSURE VALVE SEAT ABOVE SAID FLOW CONTROLLING DEVICE FOR PREVENTING THE FLOW OF FLUID UPWARDLY THROUGH SAID CASING FOLLOWING DISPLACEMENT OF SAID FLOW CONTROLLING DEVICE.
 23. APPARATUS FOR USE IN CEMENTING PIPE IN A WELL, COMPRISING THE COMBINATION OF: A PLUG SEAT HAVING MEANS FOR CONNECTING SAID SEAT IN SAID PIPE IN THE PATH OF FLUID PASSING THROUGH SAID PIPE, SAID PLUG SEAT HAVING AN OPENING FOR PASSAGE OF SAID FLUID, A PLUG HAVING THEREON MEANS SEALINGLY ENGAGEABLE WITH SAID PIPE TO MOVE THE PLUG ALONG WITH SAID FLUID INTO ENGAGEMENT WITH SAID PLUG SEAT, SAID PLUG HAVING AN EXTENSION BENEATH SAID SEALING MEANS, SAID EXTENSION BEING EXTENDIBLE INTO THE OPENING IN SAID SEAT, SAID SEAT AND SAID EXTENSION HAVING COOPERABLE MEANS FOR LATCHING SAID PLUG IN SAID SEAT UPON ENGAGEMENT THEREOF, AND SAID EXTENSION AND SAID SEAT HAVING MEANS INCLUDING COOPERABLE SEALING PORTIONS TO PREVENT THE FLOW OF FLUID UPWARDLY THEREBETWEEN. 